If you are looking to buy a green home, you likely will run into terms like passive solar, active solar, water catchment, LEED certification, xeriscaping, Earthship, pervious concrete, daylighting, etc. As sustainable architecture continues to grow in popularity, so does the vocabulary associated with it. Whether you’re searching for a new house with eco-friendly features or you’re interested in making some green upgrades to your current home, you may find the options and terminology overwhelming. To clear up some of the confusion, here are definitions of today’s most used environmental-home terms and buzzwords:

Active Solar Electricity Generation: This approach to collecting solar energy employs one or more panels comprised of photovoltaic cells (see Solar Panel) to convert the sun’s light waves into electricity. In the right climate and utilizing a large solar-panel array and ample battery storage, all the electricity needs of a home with low to moderate energy use can be supplied by the sun.

Adobe: Not only is this building material extremely durable and natural, in hot climates, it is unsurpassed in energy efficiency. Adobe bricks are made by adding a mixture of clay, sand and water to a fibrous component such as sticks or straw. A home with adobe walls is ideally suited to climates with hot days and cool nights. The high thermal mass of the bricks averages out the day's high and low temperatures, moderating the temperature of the living space. For example, the space stays warm on frigid desert nights thanks to the bricks being warmed by the sun each day. Upon nightfall, that heat then naturally transfers to the interior space.

Advanced House Framing (AKA Optimum Value Engineering): In wood-frame house construction, advanced house-framing techniques aim to use less lumber and produce less waste. Since insulation material is used in place of some of the lumber, the home has the added bonus of being more energy-efficient.

Cob Home: Similar to adobe, cob is a building material made of a mixture of sand, clay, water and dirt. Cob homes, some as old as 500 years, exist across the globe. Due to its natural components, durability and exceptional thermal-mass value, cob has enjoyed resurgence in use.

Compost: Instead of sending it to an overburdened landfill, a household that composts turns kitchen scraps, grass clippings and other plant and vegetable waste into a nutrient-rich natural fertilizer. Regularly maintained and rotated in a simple mound or container, the discarded organic matter will eventually break down into a precious soil-like substance that will help your flower and vegetable gardens thrive, save you money and benefit the Earth.

Composting Toilet: Composting toilets look much like regular toilets, but work like a backyard compost pile and use little or no water. They consist of a commode and a composting chamber—no sewer lines or septic tank (see Septic Tank System) are necessary. Once in the composting chamber, waste is broken down aerobically by bacteria, fungi or even worms. Ventilation systems bring in oxygen and also create suction into the chamber, preventing odors from escaping. Additional accessories may include mixing blades to further introduce oxygen, and a heater to maintain the optimum temperature for the microorganisms. Some models require the regular addition of peat moss or sawdust to prevent compacting, while others are capable of accepting food scraps, grass clippings and leaves.

Conservation Easement: This voluntary legal agreement between a landowner and government agency or land trust protects the natural state of the property by permanently prohibiting development and other changes. The conservation easement remains binding with all subsequent owners. If you own a large parcel of land and wish to see it protected as a wildlife habitat instead of morphing into a housing subdivision or strip mall, a conservation easement may be the perfect solution.

Daylighting: One of the most low-tech ways to make a home greener, daylighting uses strategically placed windows, skylights and light tubes in order to maximize natural daylight and minimize the need for artificial lighting.

Demand Water Heater: (See Tankless Water Heater)

Dome Home: Immune to virtually any natural disaster, a dome home is an igloo-shaped residence known for its durability and supreme energy efficiency, primarily achieved by having up to 30% less surface area enclose the same amount of space found in a conventional square-shaped home. Although its look may seem odd when viewed in the context of today's boxy abodes, it predated the current style and is making a comeback thanks to its many advantages.

Drip Irrigation: This watering system of tubes containing holes at strategic intervals will keep your flowerbeds and gardens well hydrated with minimal waste. Instead of a sprinkler system, which can wastefully spray water where it’s not needed, a drip-irrigation system is much more efficient, going straight to the roots of the plants. Much less of it evaporates, too.

EarthCraft House (ECH): Another program aimed at attaining eco-friendly homes, EarthCraft House (ECH) is a green building initiative created in 1999 that educates builders on how to construct homes that are up to 30% more energy efficient.

Earth-Sheltered Home: Not just for hobbits, a home that’s built entirely underground or banked into the Earth is a sound green choice. Earth-sheltered homes are better protected from extreme outdoor temperatures, making them superbly energy-efficient in regards to heating and cooling needs.

Earthship: Often found in the southwest US, an Earthship brings a multitude of green features together under one roof with the goal of complete self-sufficency. Typically off-grid and made of upcycled tires packed with dirt, these dwellings leverage myriad eco technologies such as daylighting, passive solar heating, thermal-mass indoor temperature control, natural ventilation and water catchment systems—to name a few.

Energy-Efficient Mortgage: If you’re passionate about purchasing an energy-efficient home but can’t afford the often-hefty price tag, you should consider an energy-efficient mortgage. Believing that lower monthly utility bills will allow you to have a larger mortgage payment, any energy-efficient features of the home are credited in the mortgage itself. Therefore, you qualify for a larger loan amount and it promotes the building of more energy-efficient homes; it’s a win-win for you and the environment.

Energy Star: No, it’s not akin to the Death Star from Star Wars. Rather, Energy Star is a government-backed initiative to promote energy efficiency. You’ve probably seen the Energy Star sticker on new appliances. When it comes to housing, everything from major household products to a newly constructed home can earn the Energy Star label when they exhibit energy-bill savings and a reduction in greenhouse-gas emissions, as defined by the Environmental Protection Agency and US Department of Energy. Not only is an Energy Star product the more sustainable choice, but it may also earn you a federal tax credit.

Geothermal Heating and Cooling: Also known as a Heat Pump), a geothermal heating and cooling systemconditions indoor space by using the Earth’s stable and renewable temperature. Regardless of whether it’s a 90-degree day or below freezing on a winter night, the Earth—possessing more thermal mass power than anything else—always remains somewhere between 45 to 75 degrees. While the initial cost of a geothermal heating and cooling system is considerably more than a standard furnace and central air-conditioning unit, cost savings are eventually achieved within five to 10 years thanks to its highly efficient nature. Furthermore, a heat pump produces significantly fewer emissions than conventional heating and cooling methods, especially when the electricity required to operate it comes from a renewable source.

Geothermal Power: Another technology using the energy of the Earth’s thermal mass, geothermal power produces electricity that is cost-effective and environmentally friendly. Traditionally limited to areas near tectonic-plate boundaries, such as Iceland and Costa Rica, recent advances have greatly expanded where it can be used. Here’s hoping that the near future brings us municipal electricity from a geothermal power plant instead of a coal-powered turbine.

GREENGUARD Indoor Air Quality Certified: Unfortunately, you’re likely to find formaldehyde in your home’s flooring and volatile organic compounds (VOC) in the insulation. When it comes time to replace these housing materials with something more environmentally sound, choose an item that’s Indoor Air Quality Certified. Household products, ranging from building materials to window treatments, are eligible for this certification when they demonstrate low particle and chemical emissions as defined by the GREENGUARD Environmental Institute, which offers a useful product search on its website.

Green Home: The term may seem vague, but according to the National Association of Home Builders, a home qualifies as green when it conserves water and other natural resources, is energy efficient, uses recycled or sustainable products, and protects indoor air quality.

Green Lease: Creating an environmentally friendly house isn’t just for homeowners. With a green lease, landlords and tenants sign on the dotted line and work together to make a home greener. The property owner typically commits to manage the rental in a sustainable way while the tenant pledges to reduce energy consumption, to recycle whenever possible and to follow other green lease terms.

Green Roof: Instead of traditional shingles, a green roofis covered with soil and plants. This single eco-friendly home feature works many wonders for the environment. Imagine a roof that absorbs the rainwater rather than corralling it into a storm sewer, provides superior insulation against both hot and cold weather, absorbs carbon dioxide, creates oxygen and helps to counteract the steamy summer temperatures in urban areas. It also looks really, really cool.

Greywater Recycling System: In the United States, where we tend to take clean water for granted, the H2O that goes down the drain after you wash dishes, do laundry or take a bath is known as greywater. It accounts for 50-80% of wastewater generated by a household. When the water from this use is diverted to the home’s toilets, you now have a greywater recycling system estimated to reduce a household’s water consumption by an average of 30%.And that’s only the beginning of what you can do with greywater.

Heat Pump: (See Geothermal Heating and Cooling)

Home Energy Audit: If you’re curious about how much energy your home uses (and wastes due to drafty windows, etc.) and want to take steps to improve its energy efficiency, consider a home e nergy audit. Options include do-it-yourself varieties and more accurate professional audits. For the latter, a professional auditor uses sophisticated equipment and techniques to make an assessment of your home’s energy efficiency.

Home Envelope: A home or building envelope is the entire exterior of your house, including the walls, roof, foundation, doors and windows. Perhaps more than any other feature, the level of environmental integrity of the home envelope is what determines your house’s degree of energy efficiency.

Instantaneous Water Heater: (See Tankless Water Heater)

LEED Certification: Standing for Leadership in Energy and Environmental Design, LEED is a green-building certification system. Covering all aspects of constructing and maintaining buildings to make them more environmentally friendly, both residential and commercial properties are eligible for LEED certification.

Light Emitting Diode (LED) Bulbs: A light-emitting diode (LED)is a semiconductor device that glows when an electric current runs through it. Used as lighting, these wonders of science last up to 50 times longer and use one-sixth the energy of incandescent bulbs; and last five times longer and use half the energy of CFLs. Their major eco-friendliness and other advantages make them ideal for home lighting and many other uses.

Low-E Windows: Good for any climate, Low-E windows are coated with layers of microscopic metallic oxide that provide great insulation. Application on outer panes blocks heat in warm climates while inside pane application helps to trap heat in cold climates.

NAR Green Designee: Similar to EcoBroker Certified, the Green Designee title is granted by the National Association of REALTORSTM when a real-estate agent has received advanced training pertaining to green real estate topics.

Off-the-Grid: A rare achievement in the United States, this is the extreme version of an eco-home. When a home is so self-sufficient that one or more public utilities are unneeded 100% of the time, it’s considered off-the-grid. Dwellings with a freshwater source, an extensive solar or wind energy setup, etc., are most apt to achieve off-the-grid status.

On-Demand Water Heater: (See Tankless Water Heater)

Optimum Value Engineering: (See Advanced House Framing)

Papercrete: A relatively new kid on the block touted as low cost and do-it-yourself, papercrete—made of paper fiber and cement—is a housing material with great insulating qualities. While it does keep some paper out of the landfill and will lower your heating and cooling bills, it’s not the most pristine green choice due to its cement component.

Passive House: Passive House is a building standard that employs ultra-tight insulation and other techniques to reduce a structure's heating and cooling energy use by up to 90%. Costing about the same as standard construction, it can be integrated into even historic buildings without changing their characters. Passive house is only now beginning to catch on in the United States, although it has long been employed in Europe.

Passive Solar Heating: This simple, design-oriented technology harnesses the sun’s heat energy without the need for mechanical or electrical devices of any kind. Passive solar heating can be as simple as having lots of south-facing windows for maximum sun exposure on cold winter days or as complex as a completely passive solar home (you can see one such model to the left), which incorporates the five elements of passive solar-home design.

Pervious Concrete: When rainwater hits conventional concrete, it runs off into an overburdened storm sewer or retention pond. Meanwhile, pervious concrete is designed to be extremely porous so that rainfall passes directly through to become groundwater, as nature intended. When the time comes to replace your driveway or any walkways, consider using this type of concrete.

Pumice-Crete: Another alternative to conventional concrete, it uses crushed volcanic rock instead of sand and gravel in order to render a lightweight yet load-bearing building material. Additionally, it’s a great insulator due to pumice’s ability to trap large amounts of air.

Radiant Heating: More efficient than baseboard or forced-air heating, and friendlier to those who suffer from allergies, radiant heating uses air, water or electricity to heat a house’s floors, walls or ceiling. They in turn heat the entire home. Hydronic radiant floors, those that use water, are by far the most environmentally friendly and efficient of the bunch. Radiant floor heating systems work best when paired with ceramic tile flooring thanks to the tile’s conduction and thermal mass properties.

Rain Garden: With the same end goal as pervious concrete, a rain garden takes the abundant rainfall runoff so common in urban areas out of the storm sewers and into a naturally depressed land area where a water-loving native garden is planted. In residential settings, rain gardens are typically placed at the exit point of a gutter downspout.

Rainwater Catchment System: When rain hits your roof and rushes into the gutter, it doesn’t have to end up in the storm sewer—not if you have a rainwater catchment system such as a rain barrel, where it’s stored until you need it to water your garden or wash your car. A more advanced system collects water in a cistern and uses a pump to distribute it throughout the house for flushing toilets and washing laundry. When the water is properly treated, cisterns can provide water for all of a household’s needs, even drinking.

Rammed Earth: Goodbye toxic building materials and deforestation, hello rammed earth. Imagine a home where the external structure can last forever and cost up to a third less than a standard frame house. Rammed earth, similar to adobe and cob, does just that. It’s made by compressing a mixture of mud, gravel, chalk and lime in reusable forms and is known for its extreme durability and excellent thermal mass properties.

R-Value: R-value measures the effectiveness of insulation materials. The higher the number, the better the insulation power and the lower your heating and cooling costs. Spray foam is an example of a type of insulation with a high R-value.

Septic Tank System: Approximately 25% of Americans use stand-alone septic systems—as opposed to tying into city-sewers—to effectively treat wastewater, and they are often the only option in rural areas. Standard septic systems consist of a tank, drainfield and the surrounding soil. The main sewer line carries all the wastewater out of the house and brings it to the underground tank—a 1,000-1,200 gallon watertight chamber made of concrete, fiberglass or polyethylene. Perforated pipes covered in gravel compose the drainfield, while the soil underneath is responsible for the majority of the wastewater treatment. Septic systems are inexpensive to maintain, but do require vigilance to insure that they don’t become the source of a problem.

Siting: One of the first concerns to be addressed when building an eco-friendly home is the critical issue of siting, in other words, choosing the greenest location to build a house? Siting takes many factors into consideration, including impact on the ecosystem, proximity to infrastructure and south-facing orientation, in order to take advantage of the sun’s warming properties.

Solar Panel: Also known as a photovoltaic module or photovoltaic panel, a solar panel is an interconnected assembly of photovoltaic cells that convert sunlight to electricity. To create an adequate amount of electricity, often several panels are joined into what is called a solar-panel array. Usually the array is connected to a battery to store the power for use at night or on cloudy days. An inverter and voltage sensing transfer switch is required to create the proper electric current for home use. Solar panels can be mounted on a rooftop or be freestanding. (See also Active Solar Electricity Generation)

Solar Water Heater: Free energy emitted by the sun can be turned into a hot shower when a solar water heater is installed on your rooftop. Simply put, it uses the sun's energy to partially or completely heat your household water supply. Because it is difficult to store heat for long periods—and you may want hot water at other times than sunny days—usually a backup heating system is required. There are several types of passive and active models, including batch, flat-plate and evacuated tube collectors.

Straw-Bale Construction: Yet another way to get load-bearing qualities and great insulation from the same renewable resource, straw-bale construction stacks bales on top of a raised foundation, ties them together and then covers them with plaster or stucco.

Super Adobe: Also known as Superblock, Super Adobe uses fabric bags filled with adobe to ultimately form sustainable dome-like structures that are extremely durable. Quite similar to the construction of wartime bunkers, Super Adobe structures go up quickly and cheaply anywhere in the world and have the same thermal mass properties as traditional adobe (see Adobe).

Sustainability: Definitely one of today’s eco-friendly buzzwords, sustainability is the extent to which something or someone can independently endure. For a home to be considered sustainable, it must be maintained over the long-term without depleting natural resources.

Sustainable Community: Imagine an entire neighborhood or town made up of sustainable infrastructure, businesses and homes whose inhabitants work together to tread more lightly on the Earth so that it remains a lovely place for all future generations. Such a community can be planned and built, or an existing neighborhood can be modified to achieve such sustainability.

Tankless Water Heater (AKA Demand, On-Demand or Instantaneous Water Heater): A conventional hot-water tank uses energy to keep water warm even when it’s not needed, making it a relatively wasteful household fixture. With a tankless water heater, whenever a hot-water tap is turned on, cold water is instantly heated as it flows through a small heating unit, thus avoiding wasted energy. Also called “demand” or “instantaneous” water heaters, they achieve the greatest efficiency gains when used in a household with lower than average hot-water consumption or when installed at each hot-water outlet.

Volatile Organic Compounds (VOCs): Don’t be fooled because “organic” is part of the name. These compounds are anything but eco-friendly, or people-friendly for that matter. VOCs are invisible gases, most often emitted by household paint, furniture and carpets, which are known to be detrimental to human health. They cause problems such as eye and nose irritation and even liver damage. You should be sure to search for low or no-VOC products, which are becoming increasingly available.

Water Well: A water well is a structure—or simply a hole in the ground—that provides access to groundwater. It is created by digging or drilling deep enough to reach an underground aquifer. The water, which can vary greatly in quality and quantity (and so may need treatment and/or softening), is drawn up in a container or by using a pump. Often it is stored in an underground or above-ground tank.

Most Americans get their water from a municipal source that's regularly checked for safety and quality. For those 15% who rely on private wells, it's very important to ensure the safety of the water from human pollutants, ranging from agricultural herbicide runoff to improper disposal of household chemicals. Several studies have linked an increased risk of Parkinson's disease to the pesticide exposure often associated with regular consumption of well water.

Wind Turbine: If you live in an open and windy area, a wind turbine may be just the ticket to lower energy bills and decrease your dependency on ubiquitous coal-powered electricity. Similar to solar panels, any excess energy generated by the turbine is stored in batteries where it can be used during non-windy times. The initial price tag is quite steep and zoning restrictions may limit your options, so be sure to do your research before investing in a wind turbine.

Xeriscaping: This approach to lawns and gardening utilizes a diverse variety of native, climate-friendly and/or drought-tolerant plants while taking measures to avoid water runoff and evaporation. Because of this, xeriscaping requires little to no supplemental irrigation and is supremely eco-friendly. Xeriscaping is an essential consideration for desert areas, like the American Southwest, where large populations are living and water supplies are dwindling.

Obviously, when it comes to eco-homes and gardens the options are exciting and abundant. Unfortunately, some of the terms and lingo can be confusing. We hope the terminology, definitions and links contained in this guide assist and inspire as you attempt some green upgrades or search for a sustainable dwelling. Best wishes for doing your part to make your home the best it can be for you, your family and the planet.

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